I have Prusa i3 derivative with MK8 extruder and Marlin 1.1RC8 as firmware. I already reduced the default speeds as well as the accelerations. But sometimes when trying to print with BQ PLA filament (220°C), mostly during filling areas, my extruder clicks. The below screenshot of Slic3rs Layers view shows the clicking "lines".
What settings I need to change to avoid the overextrusion in this case?
Are you sure it clicks exactly when retracting? Clicking mostly indicates extruder is unable to advance filament. In your case if it sounds when more filament is required (like filling areas), then you may try to reduce printing speed in such areas or increase nozzle temperature.
You are right. On a different object it becomes obvious that the clicking occurs when performing solid infill, even on a long "line". I'm using Slic3rs default values for the speed, so 20mm/s for solid infill (normal infill 50mm/s).
If reducing speed won't help, then there is something else blocking smooth filament extrusion. With PLA you are most likely using cooler. Try reducing cooler speed for areas with 100% infill. Otherwise look at @rwinscot answer.
First 220c for PLA? You must be running at record speeds! But really a video would be a lot of help :-)
@StarWind: no, this PLA is specified to use 220°C. I'm using speeds of up to 50mm/s for inner perimeters.
@ThomasS, will the print continue fine afterwards? If it does, this may simply be the issue of a too large nozzle trying to squeeze infill into a gap smaller than itself - something many slicers struggle to handle elegantly.
I've tried to reduce the "Extrusion multiplier" from 1 to 0.95, but that caused gaps. Now I've minimized the clicking by setting the Slic3r option "Infill before perimeters" on the "Print Settings > Infill" page.
PS: If the same amount of plastic still gets extruded - just in a different order - won't all parts will grow slightly in size? Also, I suspect that perimeters usually are printed first in order to get a smoother finish. Is this according to your experience? Thanks for sharing your answer. :-)
Yes, I think, that the objects will slightly wider. I don't know why usually the perimeters are printed first - can't say they look worse now.
so, here is my theory: There is the slic3r setting "Combine Infill every: X layers". What this will do if it's set to 3 for example is first print three regular sized layers of perimeters, and after that print one fat infill layer that is 3 times the layer height (that's a speed optimization). Of course this is more filament that must be pressed through the nozzle and may cause clicking. However, if you FIRST print the infill, then this optimization cannot be performed (so infill will always be printed at the set layer height rather than at a multpile of it)